@Octaf1sh You can connect both WD cloud drive and laptop via Ethernet ports to the same Deco. The data transfer will be through Ethernet connection within Deco. You could test on two other wired...

I think the "main" Deco is just to label the one that is connected to the modem via Ethernet cable. If you change another one as the "main"Deco, you might need to connect this unit to the modem via...